Diagnostic cytology, particularly in the area of clinical pathology, bases cytological interpretations and diagnoses on examination of cells and other microscopic objects. The accuracy of the screening process and diagnosis, and the preparation of optimally interpretable samples from specimens typically depends upon adequate specimen and sample preparation. In this regard the ideal sample would consist of a monolayer of substantially evenly spaced cells, which enables cytotechnologists, cytopathologists, other medical professionals, and automated screening and diagnostic equipment to view or image the cells more clearly so that abnormalities can be identified more readily, more accurately and more reproducibly. Newer methodologies such as immunocytochemistry and cytometric image analysis require preparation apparatus and methods that are safe, effective, accurate, precise, reproducible, inexpensive, efficient, fast and convenient.
Cytological examination of a sample begins with obtaining specimens including a sample of cells from the patient, which can typically be done by scraping, swabbing or brushing an area, as in the case of cervical specimens, or by collecting body fluids, such as those obtained from the chest cavity, bladder, or spinal column, or by fine needle aspiration or fine needle biopsy. In a conventional manual cytological preparation, the cells in the fluid are then transferred directly or by centrifugation-based processing steps onto a glass microscope slide for viewing. In a typical automated cytological preparation, a filter assembly is placed in the liquid suspension and the filter assembly both disperses the cells and captures the cells on the filter. The filter is then removed and placed in contact with a microscope slide. In all of these endeavors, a limiting factor in the sample preparation protocol is adequately separating solid matter from its fluid carrier, and in easily and efficiently collecting and concentrating the solid matter in a form readily accessible to examination under a microscope.
Currently, biological specimens are collected for cytological examinations using special containers. These containers usually contain a preservative and transport solution for preserving the cytology specimen during shipment from the collection site to the diagnostic cytology laboratory. Further, cytology specimens collected from the body cavities using a swab, spatula or brush are also preserved in special containers with fixatives (e.g., alcohol or acetone fixatives) prior to transferring cells onto the slide or membrane for staining or examination. Specimen containers are known that allow a liquid-based biological specimen to be processed directly in the container so as to obtain a substantially uniform layer of cells on a collection site (in a filter housing defining a particulate matter separation chamber) that is associated with the container itself. See, for example, U.S. Pat. Nos. 5,301,685; 5,471,994; 6,296,764; and 6,309,362, of Raouf A. Guirguis, all of which are incorporated herein by reference.
The filtration techniques taught in these patents in practice have yielded fairly good results in terms of obtaining close to a monolayer of cells on slides, but there is room for improvement. Further, the types of specimen containers disclosed in these patents require specially configured apertured covers and adapters therefor that are designed to mate with the filter housing, and with suction equipment (e.g., a syringe or a mechanized vacuum source) used to aspirate liquid from the container and draw it through the filter. In addition, extraction of the filter so that it can be pressed against a microscope slide to transfer collected cells to the slide requires disassembly of the cooperating parts of the cover and/or adapters associated therewith. If the processing is done by automated equipment, special handling devices are required to carry out such disassembly. All of this complexity adds time, and material and labor cost to the processing required prior to the actual cytology examination.
In general, automated equipment thus far developed for processing liquid-based specimens have not performed with sufficient consistency, reliability, speed and automation to satisfy current and projected needs in cancer screening and other cytology-based medical, analytical, screening and diagnostic procedures. The vial-based automated processing system disclosed herein provides a safe, elegant and effective solution to these problems.